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Pyridoxal phosphate promotes decarboxylation of amino acids. Flavin-dependent decarboxylases are involved in transformations of cysteine. Iron-based hydroxylases operate by reductive activation of O 2 using the decarboxylation of alpha-ketoglutarate as an electron donor. The decarboxylation can be depicted as such:
The amino acids that are produced by protein catabolism can then be further catabolized in amino acid catabolism. Among the several degradative processes for amino acids are Deamination (removal of an amino group), transamination (transfer of amino group), decarboxylation (removal of carboxyl group), and dehydrogenation (removal of hydrogen ...
The order in which the amino acids are added is read through the genetic code from an mRNA template, which is an RNA derived from one of the organism's genes. Twenty-two amino acids are naturally incorporated into polypeptides and are called proteinogenic or natural amino acids. [28] Of these, 20 are encoded by the universal genetic code.
Deamination is the removal of an amino group from a molecule. [1] Enzymes that catalyse this reaction are called deaminases. In the human body, deamination takes place primarily in the liver; however, it can also occur in the kidney. In situations of excess protein intake, deamination is used to break down amino acids for energy.
These enzymes catalyze the decarboxylation of amino acids and alpha-keto acids. [1] Classification and nomenclature
In animal tissue, BCKDC catalyzes an irreversible step [2] in the catabolism of the branched-chain amino acids L-isoleucine, L-valine, and L-leucine, acting on their deaminated derivatives (L-alpha-keto-beta-methylvalerate, alpha-ketoisovalerate, and alpha-ketoisocaproate, respectively) and converting them [3] to α-Methylbutyryl-CoA, Isobutyryl-CoA and Isovaleryl-CoA respectively.
Acetyl-CoA may then be used in the citric acid cycle to carry out cellular respiration, and this complex links the glycolysis metabolic pathway to the citric acid cycle. Pyruvate decarboxylation is also known as the "pyruvate dehydrogenase reaction" because it also involves the oxidation of pyruvate. [2]
In contrast to the relatively facile decarboxylation of β-keto acids, the decarboxylation of α-keto acids presents a mechanistic challenge. Thiamine pyrophosphate (TPP) provides the biochemical and enzymological answer. TPP is the key catalytic cofactor used by enzymes catalyzing non-oxidative and oxidative decarboxylation of α-keto acids.